Coronavirus Resource Center – Harvard Health

COVID-19 (coronavirus disease 2019) is a respiratory illness caused by the SARS-CoV-2 virus. It is highly contagious and spreads quickly.

Most people with COVID-19 have mild respiratory symptoms that feel a lot like a cold or flu. But it can be much more serious for older people, people with co-morbidities and those who have not been vaccinated against COVID-19. Some people may continue to suffer from conditions after COVID, known as “long COVID”. There is also evidence that COVID vaccines protect against prolonged COVID.

Vaccines against COVID-19 are very safe and effective. They are the best defense against the virus as they prevent serious illness, hospitalization and death.

Even if you’ve been vaccinated, you’ll want to follow public health guidelines. This may mean temporarily wearing masks indoors or avoiding large gatherings if the levels of COVID-19 in your area are high. The good news is that these steps will also reduce your risk of developing other respiratory viruses, such as a cold or flu.

We know much more about COVD-19 than we did in 2020, and yet we are still learning. We will continue to provide important updates.


Terms you should know

aerosols: infectious virus particles that can be carried or carried in the air. Aerosols are emitted by a person infected with the coronavirus – even without symptoms – when they talk, breathe, cough or sneeze. Another person can inhale these aerosols and become infected with the virus. Aerosolized coronavirus can stay in the air for up to three hours. A mask can help prevent this spread.

antibodies: proteins produced by the immune system to fight infection. If the antibodies later encounter the same infection, they help prevent disease by recognizing the microbe and preventing it from entering cells.

antibody test: Also known as a serology test, an antibody test is a blood test that looks for antibodies made by your immune system. An antibody test can show if you have been infected before, but it is not a reliable way to determine if you are currently infected.

antigen: a substance exposed on the surface of a microbe that stimulates the body to produce an immune response.

antigen test: a diagnostic test that detects specific proteins on the surface of the virus.

booster: an additional dose of the COVID-19 vaccine given after protection from the initial series of vaccines begins to wane.

community dissemination (community transmission): it is said to occur when people have been infected without knowing about contact with someone who has the same infection.

diagnostic test: indicates whether you are currently infected with COVID-19. A sample is taken using a swab from the nose, nose and throat or saliva. The sample is then checked for genetic material of the virus (PCR test) or for specific viral proteins (antigen test).

efficacy: shows the benefit of the vaccine in the real world.

efficacy: shows the benefit of a vaccine compared to a placebo in the context of a clinical trial.

epidemic: an outbreak of disease in a community or region

false negative: a test result that falsely indicates that you are not infected when you are.

false positive: a test result that falsely indicates you are infected when you are not.

herd immunity: herd immunity occurs when enough people become immune to a disease to make its spread unlikely. As a result, the entire community is protected, even those who are not themselves immune. Herd immunity is usually achieved through vaccination, but can also occur through natural infection.

immunity: partial or complete protection against a particular infection because a person has either had that infection before or has been vaccinated against it.

incubation period: the time period between exposure to infection and the onset of symptoms

insulation: separating people with a contagious disease from people who are not sick

long distance carriers: people who have not fully recovered from COVID-19 weeks or even months after the first symptoms.

mutation: A change in the genetic material of a virus that occurs when the virus replicates. The change is passed on to future generations of the virus.

monoclonal antibodies: laboratory-made proteins designed to mimic naturally occurring antibodies that target specific antigens on viruses, bacteria, and cancer cells.

mRNA: short for messenger ribonucleic acid, mRNA is genetic material that contains instructions for making proteins.

mRNA vaccines: mRNA vaccines for COVID-19 contain synthetic mRNA. Inside the body, the mRNA enters human cells and instructs them to produce the “spike” protein found on the surface of the COVID-19 virus. The body recognizes the spike protein as an invader and produces antibodies against it. If the antibodies later encounter the actual virus, they are ready to recognize and destroy it before it causes disease.

pandemic: an outbreak of disease affecting large populations or an entire region, country, or continent

physical distancing: also called social distancing, refers to actions taken to stop or slow the spread of a contagious disease. For an individual, this refers to maintaining enough physical distance (at least six feet) between you and another person to reduce the risk of inhaling droplets or aerosols that are formed when the infected person breathes, talks, coughs, or sneezes.

polymerase chain reaction (PCR) test: a diagnostic test that detects the presence of the genetic material of the virus.

postviral syndrome: the constellation of symptoms experienced by long-haul carriers of COVID-19. These symptoms may include fatigue, brain fog, shortness of breath, chills, body aches, headache, joint pain, chest pain, cough, and prolonged loss of taste or smell.

SARS-CoV-2: short for severe acute respiratory syndrome coronavirus 2, SARS-CoV-2 is the official name of the virus responsible for COVID-19.

spike protein: a protein on the surface of the SARS-CoV-2 virus that binds to and allows the virus to enter human cells.

option: A virus containing one or more mutations that make it different from a circulating version of the virus.

Variants of anxiety: SARS-CoV-2 viruses with mutations that make them more likely to spread, evade vaccines, or make people sick.

vector: harmless capsule. In a vaccine, a vector may be used to deliver a substance into the body to induce an immune response.

virus: a virus is the smallest of infectious microbes, smaller than bacteria or fungi. A virus consists of a small piece of genetic material (DNA or RNA) surrounded by a protein coat. Viruses cannot survive without a living cell in which to reproduce. Once a virus enters a living cell (host cell) and takes over the cell’s internal workings, the cell cannot perform its normal life-sustaining tasks. The host cell becomes a factory for virus production, creating virus parts that are then reassembled into whole viruses and go on to infect other cells. Eventually the host cell dies.

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